Furnaces, process ovens and burn-off ovens use a temperature controlled, highly heated atmosphere to accomplish their designated objective. A "charge" of materials for processing is placed in an insulated primary chamber which is fired with combustion gases. A circulation pattern in the oven interior is initiated by the burner discharge flow, or by a separate blower, passes through or around the charge, is continued by convection and completed by the low pressure of exhaust stack draft and/or aspiration into an afterburner system.
Practitioners of the art have given us various methods for control of oven atmosphere distribution, frequently involving mechanically forced flow, as by fans, or multiple burner discharge locations. Such means have generally been adequate, albeit at the expense of greater capital expense and/or increased maintenance requirements. There is a continuing need for means to achieve uniform temperature distribution in ovens, in a form that is adaptable to all types of oven and inexpensive to manufacture.
Objects of the present invention therefore, are to provide a system and means for inducing operating atmosphere circulation to provide uniform temperature distribution and eliminate "dead spots" of stagnate gases, and "hot spots" such as caused by burner gases in a gas or oil fired oven. A second object is provide such a system without the expense and maintenance required by fans or mechanical means and yet another object is to achieve better energy efficiency for ovens.
The present invention addresses these objects with a gas flow directing and mixing device which can be adapted to virtually any oven application. Burner gases are directed into a distribution chamber, which is preferably located against an oven wall. The burner gases then flow outwardly from that chamber, through directionally oriented venturi-like ducts, so as to spread out and flow along the oven wall. Oven gases, drawn in through openings that communicate with the venturi-generated low pressure zones, mix with the burner gases and create a pattern of circulation throughout the oven interior. Thusly, in the present invention, the enhanced velocity of burner gases is used to provide uniform temperature distribution in ovens, without the need for fans or other additional complexities. In burn-off ovens, the oven gases will include combustible vapors, which provide a source of "free fuel" when drawn in and mixed with burner gases in the venturi mixer of the present invention.